Stuff about set Multiset map multimap

A lot of interviewers like to ask the candidates the difference between set and Multiset (MAP and multimap). What does multi actually mean? Multi-container cocould have duplicate element. Check the code below.

  1 /*********************************************  2 Author:Zhou You  3 Time:2014.09.06  4 Feature:comparison of containers such as set,multiset,map and multimap.  5 *********************************************/  6   7 #include <iostream>  8 #include <string>  9 #include <map> 10 #include <set> 11  12 using namespace std; 13  14 class setdata 15 { 16 public: 17     setdata(): 18         data_(0){ 19     } 20     setdata(int data): 21         data_(data){ 22     } 23     ~setdata(){} 24  25     bool operator<(const setdata &data) const{ 26         return data_<data.GetData(); 27     } 28  29     int GetData() const{ 30         return data_; 31     } 32  33 private: 34     int data_; 35 }; 36  37 struct mapcmp 38 { 39     bool operator()(const int &data1,const int &data2){ 40         return data1<data2; 41     } 42 }; 43  44 set<setdata> set_int; 45 multiset<setdata> multiset_int; 46 map<int,string,mapcmp> map_intstr; 47 multimap<int,string,mapcmp> multimap_intstr; 48  49 int main() 50 { 51     //for set 52     set_int.insert(setdata(1)); 53     set_int.insert(setdata(20)); 54     set_int.insert(setdata(14)); 55     set_int.insert(setdata(23)); 56  57     cout<<"output set container data"<<endl; 58     for(set<setdata>::iterator iter = set_int.begin();iter!=set_int.end();++iter){ 59         cout<<iter->GetData()<<" "; 60     } 61     cout<<endl<<endl; 62  63     //for multiset 64     multiset_int.insert(setdata(1)); 65     multiset_int.insert(setdata(20)); 66     multiset_int.insert(setdata(20));//insert 20 again. 67     multiset_int.insert(setdata(14)); 68     multiset_int.insert(setdata(23)); 69  70     cout<<"output multiset container data"<<endl; 71     for(set<setdata>::iterator iter = multiset_int.begin();iter!=multiset_int.end();++iter){ 72         cout<<iter->GetData()<<" "; 73     } 74     cout<<endl<<endl; 75  76     //for map 77     map_intstr.insert(pair<int,string>(9,"chen")); 78     map_intstr.insert(pair<int,string>(2,"wang")); 79     map_intstr.insert(pair<int,string>(13,"wu")); 80     map_intstr.insert(pair<int,string>(7,"tang")); 81  82     for(map<int,string>::iterator iter = map_intstr.begin();iter!=map_intstr.end();++iter){ 83         cout<<iter->second<<" "; 84     } 85     cout<<endl<<endl; 86  87     //for multimap 88     multimap_intstr.insert(pair<int,string>(9,"chen")); 89     multimap_intstr.insert(pair<int,string>(2,"wang")); 90     multimap_intstr.insert(pair<int,string>(13,"wu")); 91     multimap_intstr.insert(pair<int,string>(13,"wu"));//insert wu again. 92     multimap_intstr.insert(pair<int,string>(7,"tang")); 93  94     for(map<int,string>::iterator iter = multimap_intstr.begin();iter!=multimap_intstr.end();++iter){ 95         cout<<iter->second<<" "; 96     } 97     cout<<endl; 98  99     return 0;100 }

In both map and set, I define Compare function myself.

Stuff about set Multiset map multimap